Intermanual difference in the Japanese Trail Making Test and its mirror version: intra-subject comparison of the task-completion time, cognitive time, and motor time.

PURPOSE

To investigate intermanual differences in the performance of the Japanese Trail Making Test (JTMT) using an intra-subject comparison, and to investigate how the cognitive and motor times spent in performing the task were related with the total completion time.

METHODS

All subjects performed both parts A and B of the following three tasks: JTMT with the right hand (R); JTMT with the left hand (L); and a mirror version of the JTMT with the left hand (M). The order in which these three tasks were performed (RLM, RML, LRM, LMR, MRL, and MLR) was randomly determined. An interval of 4 weeks was scheduled between each examination. In addition to the completion time, we measured 'motor time', a sum of the times for drawing lines to connect the targets, and 'cognitive time', a time obtained by subtracting the motor time from the completion time.

RESULTS

The task-completion time was more strongly correlated with the cognitive time than with the motor time. The order of the task performance did not influence the task-completion time. A learning effect was found only between the first and second examinations of part A. The cognitive time for the second and third performances of part A were significantly shorter than that for the first task, whereas the motor time remained unchanged. No intermanual differences in the performance were found in any comparisons.

CONCLUSIONS

The non-dominant hand can be used as an alternative hand in the JTMT, and it can be expected to perform comparably to the dominant hand. These findings are consistent with the finding previously obtained by inter-subject comparison. The lack of any significant intermanual difference can be explained by that the total completion time is less influenced by the motor time than by the cognitive time.